I have three thoughts about this:
1. I have long admired the possibility that books whose sales may not warrant keeping in print but whose value in classrooms and as scholarly works persisted. I am thinking in part of the WAC Clearinghouse project, which makes (for example) Charles Bazerman's rhetoric of science classic available here: http://wac.colostate.edu/books/bazerman_shaping/ I see this move as part of that.

2. At the same time, man, I would hate to be a grad student who could not annotate a paper text. What do today's grad students do? Do any Blogora readers assign e-books in grad seminars?

3. The library collection thing also interests me. Our library has some e-books that barely count as e-books, insofar as they are page-view based documents that must be read online, while other allow whole chapter pdf download. What is the action at your institution, and again, can you teach from it?